Non-volatile memories have been used in storage devices of information processing systems. Such non-volatile memories correspond to electrically erasable and programmable read only memories (EEPROMs), resistance random access memories (ReRAMs), and the like. These non-volatile memories can maintain stored data even when their power is off and thus a power supply is disconnected.
However, a phenomenon of stored data being corrupted in such non-volatile memories is known. ReRAMs, for example, are memories in which resistance values of memory elements inside memory cells are set to be in a high-resistance state or a low-resistance state, and data is stored by associating the state of the resistance values with a logical value. Then, there may be a case in which a resistance value of the memory elements changes as time passes, and thus it is not possible to determine whether they are in the above-described high-resistance state or low-resistance state. In this case, the stored data is eventually corrupted.
As a countermeasure therefor, data stored in memory cells is preserved in a temporary data preserving area to erase the stored data from the memory cells. A storage device which subsequently restores the data preserved in the temporary data preserving area by, i.e., performing refresh, has been proposed (for example, refer to Patent Literature 1).